# Generic Cell Rate (GCR) algorithm
[](https://crates.io/crates/gcr)
[](https://docs.rs/gcr)
A fast, simple, and small Generic Cell Rate (`GCR`) algorithm implementation with zero dependencies
that allows for dynamic rate adjustment.
# Usage
```rust
use gcr::Gcr;
let mut rate = Gcr::new(10, Duration::from_secs(1), Some(30)).unwrap();
// 10 units allowed every second with a max burst of 30 units at once
rate.request(20).unwrap(); // Leftover capacity is now 10
rate.request(20).unwrap_err(); // Returns `DeniedFor(1 second)`
```
## Rate adjustment
[`Gcr::adjust`] can be used to change the rate of the limiter while preserving the current capacity.
It accepts the same parameters as [`Gcr::new`].
```rust
rate.adjust(20, Duration::from_secs(1), Some(30)).unwrap();
// 20 units allowed every second with a max burst of 30 units at once
```
## Capacity
[`Gcr::capacity`] can be used to get the current capacity of the rate limiter without making a request.
```rust
rate.capacity();
```